Torque wrench



J. REILLY ETYAL 2407,45@

TORQUE WRENCH Filed Dec. 17, 1945 2 sheets-sheet 1 Sept. 10, 1946.

Sept. 1o, 1946. J, REILLY Er AL 2,407,450

TORQUE WRENCH Filed Dec. 17, 1945 2 Sheets-Sheet 2 INSULATION JOE Eff/JJ. Genes M @El/.Ln

Patented Sept. 10, 1946 UNITED STATES PATENT OFFICE TORQUE WRENCH Joe Reilly and Grace M. Reilly, Elmhurst, lll.

Application December 17,

Our invention' relates to wrenches, particularly power operated torque wrenches for applying fastening devices such as nuts, bolts, screws or the like.

An important object of the invention is to provide a wrench in which an electro-magnetic coupling or clutch is included in the driving connection between the driving motor and the tool which is to be applied to the devices to be fastened. l

A further object is'to provide an arrangement in which a helical spring and a magnetic coupling are included in the driving connection between the motor and the tool and cooperate to apply torque to the tool.

A further object is to provide a wrench in which an electro-magnetic clutch is included in the driving connection between the motor and the tool, with the circuit for the electro-magnet winding automatically controlled for release of the tool from further drive torque as soon as the drive torque effort has reached a predetermined maximum.

Still a further object is to provide an arrangement in which the electro-magnetic clutch is automatically rendered inoperative to apply further torque to the tool when the torque has reached a predetermined maximum.

On the drawings which disclose our improved wrench,

Figure 1 is a side-elevation section;

Figure 2 is an enlarged section on plane II-II Figure 1;

Figure 3 is an enlarged section on plane III-III Figure 1; and

Figure 4 is a view on plane IV-IV Figure 2.

Referring to Figure 1, l designates a cylindrical housing in the upper part of which a driving motor such as an electric motor M is mounted. In the housing l0 below the motor is a cross frame Il in which is journaled the shaft I2 with which the motor shaft i3 is connected through a suitable reduction gearing train M. The shaft I2 at its lower end extends into the hub i5 of a cupped or bell-shaped driving member I6, a key I1 securing the shaft to the hub. The driving member IE extends down into the housing por'- tion i8 which is secured to form a continuation of the motor housing end is closed by a detachable cap I9.

Within the housing part i8 is the electromagnetic couplingor clutch. This coupling or clutch comprises the armature or driving drum 20 whose hub 2| receives the shaft 22 which expartly in diametral I0 and which at its lower 6 Claims. (C1. 19.2-150) 1943, Serial No. 514,650

tends downwardly through the bearing hub 23 on the housing cap I9. The shaft 22 has a seating collar 24 secured thereto for seating against the inner side of the bearing hub 23, an antifriction bearing 25 being preferably interposed. A distance above the seating collar 2A, the shaft has another seating collar 26 secured thereto against which the hub 2i of the drum 20 seats, with an anti-friction bearing 21 preferably interposed. At its upper end the shaft 22 extends into the hub I5 of the driving member i6. A helical or torsion drive spring 28 encircles the shaft 22 and extends between the top of the drive member I6 and the top of the armature drum 20, the upper end of the spring being anchored in an opening 29 in the driving member I6 and the lower end of the spring being anchored in the opening 30 in the top of the armature drum, so that when the driving member I6 is rotated by the driving motor in the housing HJ, such rotation will be transmitted through the spring 28 to the armature drum 20.

Within the armature drum 20 is an electromagnet E which comprises the ring 3l of magnetizable material such as iron and which is of U-shape cross-section, vthis ring being carried by a spider 32 whose hub is keyed to the shaft 22 below the collar 23 thereon. The outer endsl of the ring legs are slotted transversely to provide upper and lower circumferential rows of poles 33 and 34, respectively. Within the ring between its pole legs is an energizing winding 35 for receiving direct current so that the poles in one row will all be positive and the poles in the other row will be negative. The cylindrical part of the armature drum 22 which surrounds the electro-magnet ring, is spaced from the ring by a narrow gap and is slotted axially to leave a circumferential row of teeth 36 for functioning as keepers for the poles 33 and 34 on the electro-magnet ring so that when current'ows through the winding for energizaticn of the ring, the arma-ture drum will be magnetically coupled to the electro-magnet for transmitting the rotation of the drum to the shaft 22 and to a tool 31 secured to the lower end cf the shaft. Eddy currents set up in the armature drum by the magnetic flow will assist in holding the drum and the electro-magnet coupled together.

For connecting the electro-magnet winding 35 for receiving current flow, slip rings 38 and 3S are mounted on the shaft 22 and insulated therefrom, these slip rings being connected with the terminalsof thewinding. A bracket @t mounted Within the cap I9 carries contact brush structures 4I and 42 engaging the slip rings.

The tool 31 may, as shown, be a `socket for receiving nuts or heads of screw bolts, or the tool may be in the form of a screw driver or other device. In order to prevent overturning of a nut or screw, which might result in stripping of threads or breakage of a screw, provision .is made to open the energizing circuit for the electromagnet winding when the torque effort on the tool has reached a predetermined maximum. With the structure shown, the circuit for the elec,- tro-magnet winding is automatically opened after a predetermined continuing driving movement of the driving member I6 when. a nut or screw has been tightened to the extent that itV will of'- fer suilicient resistance to theinormaltorquei effort of the spring 28 to cause the electro-magnet coupling to slow down and lag behind the driving member I6. The driving member will then be rotated by the driving motor a distance independently of the electro-magnet clutch during which independent movement the driving spring 28.will be wound up to increase its torque effort for a final turning movement of the tool through the electro-magnet coupling for final setting of the nut or screw, whereafter the electro-magnet winding circuit Iwill be opened. The means for accomplishing all this is clearly shown on Figures. 1, 2 and 3. An annular cap 43A of insulating material receives the upper corner. of the drum 2.0 with. its. side wall supporting the slip ring 44` which is engaged by a contact. brush 45 on a terminal screw 46 extending through` but insulatedfromthe housing part I8, the terminal screw being connected by conductor 4'lv with the brush structure 4.2 for the slip ring 39 for the electro-magnet winding. AnY annular'. cap 48 of insulatingy material receives the lower end of the driving member I 5. and mounts a slip ring 4'9 engaged by a contact brush 50 on the terminal screw 5I extending through but insulated from the housing part I8. Mounted on the lower. wall 48"` of; the `cap 4'8 is ak contact brush 52 which is electrically connected with the slip ring 49 bya connection 53 (Figure 2). The brush 52 extends downwardly for contacting theY arcuate contact plate 54 on the upper wall of the insulation cap connected with the slip ring 44 on the drum through the connection 55.

Referring to Figure 1, the legv 55of the supply line C for the electro-magnet winding extends to vthe follO-ws the driving member, the brush 52. on the driving element I 6 will remain in Contact with the contact plate 54 on the coupling drum.

However, as soon as the nut o1" screw engaged 75 rush structure4l for the slip` ring 38 of i' by the tool approaches its final setting and resists turning movement by the tool, the driving member I6 will continue its rotation relative to the slowed down coupling for the nal torque effort by the spring 28 for rlnal setting of the screw or bolt, the brush 52 then leaving the contact plate 54 to open the electro-magnet winding circuit. The wrench is then withdrawn from the nut or screw and the spring. 2B will then return` the driving member IB to its.` normal position relative to the coupling drum for reengage ment of the brush 52 with the contact plate 54, the wrench being then ready for another` driving operation.

Means areprovided whereby the operator may set the wrench for the desired nal setting of a nutoi. serew'by `thextool in order to avoid overturning of the screw or nut which might result in stripping of threads or :breakage of the nut or screw. This setting arrangement is best shown on Figures Zand- '1i'.` The"armular"capk 14E-ismtatable'on the. drivingmemher I6v .for setting' of the contactrbrush. 52frelative to-thefcontaact plate 54. The cap 48 has the slot 58 therein through which extendsV a guide 'and'. locking: lscrew 59 which threads into the `driving;member. I6. The cap may' have another slot 50 oppositeetherslot 58 into lwhich a guide; pin 5I extendsfrom the driving member I6; thescrew `5I! and the pin. '64 thus serving to hold the cap to the drive member yI6 and to guide its adjustment` movement. In order to enable the cap tov beneadily rotatably adjusted, a hole 62 may be provided therein. into which a` point or ltool maybe inserted..for .rotational adjustment of the cap; This holei iseaccessiblel through the circumferentially extending slot 5.3 in the-v housing part I8.- A'scaleu# on the driving mem-ber labove the cap: 48 will cooperate with ampointer P on the. cap toy indicate the position of the brush 52 relativeA to the contact plate 54 (Figure 4i'. `After adjustment 0f the-cap for setting of the brush 52, the screw 59 may be drawn up to lock the caplin its set position. .FiguresZ and134 show the-brushu52fset for engagement with thejplate 54vnear the forward.A endof' thel plate; this .being thenormalpm sition. During; operation of the wrenchto turn a nut or screw, the-driuingmember I6. and the electro-magnetic. couplingv4 rotate together with the brush 52 retaining its normal position .oni-.thc plate 5,4. When the Vnui; ory screw approachesfits final setting and its resistance tends to stopithe rotation of the coupling. thefdriving membery I6 will continue and through the spring 28 wilLex ert the lnalsetting torque onthe tool.v through the coupling, the brush 52 during sucht-nal setting movement being carried with. the driving member. I5. forwardly along. the contact platev 54 to be. disengaged therefrom` forl opening. ofv the electro-magnet windingV circuit at the end .of the Iinal setting or'. torque applicationof the wrench to the nut or screw.

The electro-magnetic clutch should .be oper.- ated by direct current, and. where. the `driving motor M is a direct .current motor, the. current supply could. be from a direct current line L. The circuit C could be connected through a switch A with thev supply lineand the. motor. M could be connected througha switch, B with. the supply line. Where. the. driving. motor is. to be connected with. an. alternatingv current.kpower line, a. direct current..source,.suchv as a. battery, wouldhave to .bei provided for the-electrmagnet circuit, with a. switch. .for the electro-magnet circuit. and with another :switch for .the alternating current motor circuit. Where the direct current and alternating current circuits are controlled by .separate switches, only the electromagnet circuit would be automatically opened at the end of final torque application to the tool and screw or nut engaged thereby. Where direct current is used both for the driving motor and the electro-magnet circuit, the motor circuit and electro-magnet circuit could be in series so that both these circuits would be automatically opened at the end of the final torque application by the wrench. After a final setting torque has been applied to a fastening device such as a nut or bolt, and the circuit is automatically opened, the wrench will be withdrawn from the device and the spring 28 will then return the driving member I6 to its normal position relative to the coupling drum for re-engagement of the brush 52 with the contact plate 54. When the wrench is no longer to be used, the switches A and B are set for opening of the motor and electro-magnet circuits.

We have thus produced a practical and efficient torque wrench in which an electro-magnetic coupling transmits driving power from a driving element to a tool and thereby eliminates mechanically inter-engaging transmission parts with resultant wear and tear. With our improved wrench, the fastening device engaged by the tool can be given a predetermined final setting movement without injury to the device, the release of torque application to the device being automatically accomplished at the end of the final setting movement.

We have shown a practical and efficient embodiment of the features of our invention, but do not desire to be limited to the exact construc tion, arrangement, and operation shown and described as changes and modifications may be made without departing from the scope of the invention.

We claim as our invention:

l. A torque device comprising a driving motor, a driving member driven by said motor, an electro-magnetic coupling comprising an armature drum and an electro-magnet, a driving connection between said driving element and said drum including a torsion spring, a driven shaft on which said electro-magnet is mounted, and means for controlling the energization of the electro-magnet winding for electro-magnetic transmission by the coupling of the driving power to the driven shaft.

2. A torque device comprising a motor driven driving member, an electro-magnetic clutch cornprising a drum and an electro-magnet within the drum having a winding thereon, a resilient driving connection between said driving member and said drum, a driven member mounting said electro-magnet, an electrical circuit for the electro-magnet winding, contacts on said driving member and drum normally in electrical engagement for closing said circuit, said driving member by virtue of said resilient connection being rotatable by said motor relative to said drum for separation of said contacts and opening of the electro-magnet winding circuit when said electromagnetic clutch is slowed down by the resistance of the driven member.

3. A torque device comprising a motor driven driving member, an electro-magnetic coupling comprising an armature drum and an e1ectromagnet having an energizing winding, a helical transmission spring connecting said driving member with said drum, a driven member mounting said electro-magnet, an energizing circuit for said winding, contacts on said driving member and said drum normally in engagement for closing said-energizing circuit whereby said coupling will rotate with said driving member to apply torque to the driven member for movement thereof toward a predetermined final position, said driving member by virtue of said helical spring being rotated relative to said coupling when said coupling is slowed down by the resistance of the driven member when approaching its final position to thereby partially wind up said spring for increased torque on said coupling to overcome the resistance of the driven member and for setting thereof into its final position, and means whereby said contacts will be disengaged at the end of the final setting movement for opening of the electro-magnet winding circu't and release of the coupling.

4. A torque device comprising a rotatable driving member, a driven member, an electro-magnetic clutch comprising an armature element and an electro-magnet element, a torsion spring for transmitting the rotational movement of said driving member to one of said coupling elements, the other coupling element being connected with said driven member, a circuit for the winding of said electro-magnet for energization thereof to electro-magnetically hold the coupling elements together, cooperating contacts for said circuit on said driving member and the clutch element connected therewith, said contacts engaging for closure of said circuit when the energized coupling rotates with said driving member whereby said driven member will be rotated, said driving member by virtue of said torsion spring being rotatable relative to the coupling when the resistance of the turned driven member retards the coupling, said contacts being disengaged after a predetermined distance of relative movement of said driving member for opening of said circuit and release of the coupling, said spring during said relative movement increasing its torque effort on the coupling for turning of the driven member to its final position.

5. A torque device comprising a rotatable driving member, a driven member, an electro-magnetic clutch comprising an armature element and an electro-magnet element, a torsion spring for transmitting the rotational movement of said driving member to one of said coupling elements, the other coupling element being connected with the driven member, a circuit for the winding of said electro-magnet for energization thereof to electro-magnetically hold the coupling elements together, cooperating contacts for said circuit on said driving member and the clutch element connected therewith, said contacts engaging for closure of said circuit when the energized coupling rotates with said driving member whereby said driven member will be rotated toward a predetermined final position, said driving member by virtue of said torsion spring being rotatable relative to the coupling when the resistance of the turned driven member retards the coupling, said contacts being disengaged after a predetermined distance of relative movement of said driving member for opening of said circuit and release of the coupling, one of said contacts being adjustable relative to the other Contact whereby to predetermine the distance of relative movement of said driving member before said contacts are disengaged, said spring during said relative move- T 5 ment increasing its torque effort on the coupling for turning of the drivenmember toits iinal position.

6. In a. torque device, a driving member, a

driven member to be turned, an electro-magnetic coupling comprising an armature element and an electro-magnet element having a, winding thereon, said driving member having resilient; driving connection with one of said coupling elements and the other coupling element being connected to said driven member, a, circuit for said wind- JOE REILLY. GRACE M. REILLY. 

